Production Simulation of Stimulated Reservoir Volume in Gas Hydrate Formation with Three-Dimensional Embedded Discrete Fracture Model
南海神狐区域的天然气水合物（NGHs）沉积在低渗透的粘土质粉砂岩中。作为一种低碳排放的可再生能源，NGH的开采和采收率很难满足工业需求。研究经济上可行的天然气水合物开发方法对于可持续能源发展至关重要。水力压裂是提高流体流动能力的有效改造技术。本文开发了一个高效的三维嵌入离散裂缝模型（EDFM），用于研究水力压裂气藏水合物储层的生产模拟，考虑了改造储层体积（SRV）。
该模型应用于垂直井、水平井和复杂结构井的水力压裂生产评估。为了验证方法的可行性，为不同类型的井和不同的裂缝建立了三个测试案例。研究了裂缝位置、裂缝导流能力、裂缝半长度、和改造储层体积大小对气体生产的影响。结果表明，多级压裂水平井的生产增加明显，而螺旋多边井对裂缝的敏感性较低。适当的改造储层体积大小可以获得高气体产量和生产效率。
CMG软件应用情况
本文中，CMG软件的GEM模块被用于模拟神狐海域水合物储层的水力压裂效果。通过使用CMG的GEM模块，研究者能够模拟气体注入水合物储层的EDFM，并且模拟了纯组分气体注入方案，如甲烷、乙烷和丙烷。
Abstract
Natural gas hydrates (NGHs) in the Shenhu area of the South China Sea are deposited in low-permeability clayey silt sediments. As a renewable energy source with such a low carbon emission, the exploitation and recovery rate of NGH make it difficult to meet industrial requirements using existing development strategies. Research into an economically rewarding method of gas hydrate development is important for sustainable energy development. Hydraulic fracturing is an effective stimulation technique to improve the fluid conductivity. In this paper, an efficient three-dimensional embedded discrete fracture model is developed to investigate the production simulation of hydraulically fractured gas hydrate reservoirs considering the stimulated reservoir volume (SRV). The proposed model is applied to a hydraulically fractured production evaluation of vertical wells, horizontal wells, and complex structural wells. To verify the feasibility of the method, three test cases are established for different well types as well as different fractures. The effects of fracture position, fracture conductivity, fracture half-length, and stimulated reservoir volume size on gas production are presented. The results show that the production enhancement in multi-stage fractured horizontal wells is obvious compared to that of vertical wells, while spiral multilateral wells are less sensitive to fractures due to the distribution of wellbore branches and perforation points. Appropriate stimulated reservoir volume size can obtain high gas production and production efficiency.
Keywords:
low-permeability gas hydrate reservoir; numerical simulation; embedded discrete fracture model; hydraulic fracturing; stimulated reservoir volume
作者单位
中国石油大学（华东）教育部非常规油气开发重点实验室，石油工程学院
